Thyroid dysfunction is frecuent in psychiatric outpatients and in the general Chilean population but there is no information about the prevalence of thyroid diseases in Chilean psychiatric inpatients. Aim: To retrospectively assess the frequency of thyroidal diseases in psychiatric inpatients. Material and Methods: Clinical charts and thyroid assessment of 241 psychiatric inpatients (147 women, mean age 33±16 years) attended in a University Psychiatric Clinic, were reviewed. Psychiatric diagnosis at discharge was made according to DSM IV criteria and endocrine diagnosis was made based on international criteria. Results: Forty nine patients (20.7%) had thyroid abnormalities. Forty four patients had hypothyroidism (18.3%) and five had hyperthyroidism (2.35%). No specific associations were found between gender or psychiatric diagnosis and endocrine abnormalities. Conclusions: In this sample, the prevalence of thyroid abnormalities was similar to other reports in psychiatric inpatiens and higher than in the general population in Chile